The present invention is related generally to disposable packages for dispensing a liquid from a container with a controlled rate of flow which is independent of the viscosity of the liquid at the time of dispensing and is more particularly concerned with such a package for dispensing syrup mixtures for use in a post-mix beverage dispensing system and a device for compensating for changes in the viscosity related to temperature variations in the syrup being dispensed.
Until recently, the majority of commercially available post-mix carbonated beverage dispenser units have been designed for large volume commercial uses such as in fast food restaurants. More recently, however, some attempts have been made in the beverage dispenser industry to reduce the cost, size and weight of post-mix beverage dispenser units sufficiently to make them available for use by the general public. Exemplary of such units are those shown in U.S. Pat. Nos. 4,306,667 to Sedam et al. and 4,493,441 to Sedam et al. Both of these patents are assigned to the assignee of the present application. The post-mix beverage dispensing units shown in these patents have been designed for placement in refrigerators, such as that shown in U.S. Pat. No. 4,306,667, and as free standing systems having refrigeration means incorporated therein, such as the system shown in U.S. Pat. No. 4,493,441. The disclosures of these two patents are, to the extent pertinent, incorporated herein by reference.
Basically, all such post-mix carbonated beverage dispensing systems utilize and mix three different ingredients to produce the resulting beverage. Those ingredients are a flavored syrup, water and CO.sub.2. For such systems to be accepted by the consuming public, the supplies of those ingredients must be capable of being quickly and easily replenished during use by an unskilled consumer.
Preferably, the syrup component is made available to the consumer in a disposable package available at supermarkets. An exemplary disposable syrup package of the prior art which may be used in the small post-mix beverage dispensing systems is disclosed in U.S. Pat. No. 4,216,885 to Sedam et al. This patent is also assigned to the same assignee as is the present invention and is, to the extent pertinent, incorporated herein by reference. The Sedam syrup package incorporates a flow control tube. In this arrangement, the tube is prepositioned at manufacture to accommodate the desired flow under the expected temperature conditions. That is, the position of the tube is such that it operates to control the flow of syrup from the package at the working ambient temperature in which the syrup is to be utilized, i.e., that of a refrigerated compartment.
A similar arrangement is shown in my co-pending application Ser. No. 918,714 which was filed on Oct. 14, 1986, entitled DISPOSABLE SYRUP PACKAGE HAVING INTEGRAL DISPOSABLE VALVE ASSEMBLY. This application is again assigned to the assignee of the present invention and is, to the extent pertinent, incorporated herein by reference. The flow control tube in this application operates similarly to that disclosed in the Sedam patent discussed above.
In use, however, the syrup packages are not always maintained at a single precise, refrigerated temperature. Often, the syrup packages are stored at room temperature. Therefore, when a new package is inserted into the post-mix beverage dispensing system, a considerable period of time is required in order for the syrup to reach the desired uniform cold temperature for which the package was designed. During the transition period, if the consumer desires to draw a beverage from the dispensing system, due to the decreased viscosity of the syrup at the elevated temperature, it is quite possible for an inordinately large amount of syrup to be dispensed thereby deleteriously altering the flavor of the beverage produced.
One means by which such viscosity changes may be overcome is through the use of a metering device such as is shown in U.S. Pat. No. 3,658,216 to Schwartzman. In a metering device, a first valve is opened to permit the flow of fluid into a reservoir, the bottom of which is blocked by a second valve. When the reservoir is full, the first valve closes and the second valve is opened allowing the predetermined metered quantity of fluid to be dispensed. Such a metering device is relatively complex and is subject to failure if either of the valves fails to seat properly.